# Help with this question

1. Mar 2, 2004

### jlmac2001

Find the position of the cnter of mass and moment of inertia for rotations about an axis through the origin and along axis of symmtry of a thin hemisphericl shell of radius R and mass M whose center is at the orgin.

For this problem, would I treat is kinda like a sphere? How would I do something like this?

2. Mar 3, 2004

### matt grime

If you keep posting every question you're set in this course you're going you're going to get some nastier responses than this.

There have been several responses showing you how to find moments of inertia; perhaps it's time you solved this one on your own? You have the formulae, you've seen the examples, show us what you've done so far.

3. Mar 3, 2004

### jlmac2001

sorry

If I knew how to do it, i would not have posted. Thanks anyway.

4. Mar 3, 2004

### matt grime

lots of people post without actually attempting to solve the problem first. Maths problems aren't supposed to be easy, and once you're onto sufficiently hard material then it should take you quite a while to solve the problems. don't give up instantly, which is what most people do when they don't see the solution immediately. that isn't how maths really works.

there seems to have been a spate of people posting messages that read 'for god's sake don't be so lazy/stupid', but slightly more confrontationally, recently, so I thought I'd warn you you might get some answers you didn't want.

so, how do you think you do the question? where would you start, where do you get stuck?

matt